Fractional location problems

In this paper we analyze some variants of the classical uncapacitated facility location problem with a ratio as an objective function. Using basic concepts and results of fractional programming, we identify a class of one-level fractional location problems which can be solved in polynomial time in terms of the size of the problem. We also consider the fractional two-echelon location problem, which is a special case of the general two-level fractional location problem. For this two-level fractional location problem we identify cases for which its solution involves decomposing the problem into several one-level fractional location problems.discrete location;fractional program

A new algorithm for generalized fractional programs

A new dual problem for convex generalized fractional programs with no duality gap is presented and it is shown how this dual problem can be efficiently solved using a parametric approach. The resulting algorithm can be seen as “dual†to the Dinkelbach-type algorithm for generalized fractional programs since it approximates the optimal objective value of the dual (primal) problem from below. Convergence results for this algorithm are derived and an easy condition to achieve superlinear convergence is also established. Moreover, under some additional assumptions the algorithm also recovers at the same time an optimal solution of the primal problem. We also consider a variant of this new algorithm, based on scaling the “dual†parametric function. The numerical results, in case of quadratic-linear ratios and linear constraints, show that the performance of the new algorithm and its scaled version is superior to that of the Dinkelbach-type algorithms. From the computational results it also appears that contrary to the primal approach, the “dual†approach is less influenced by scaling.fractional programming;generalized fractional programming;Dinkelbach-type algorithms;quasiconvexity;Karush-Kuhn-Tucker conditions;duality

Fractional location problems

In this paper we analyze some variants of the classical uncapacitated facility location problem with a ratio as an objective function. Using basic concepts and results of fractional programming, we identify a class of one-level fractional location problems which can be solved in polynomial time in terms of the size of the problem. We also consider the fractional two-echelon location problem, which is a special case of the general two-level fractional location problem. For this two-level fractional location problem we identify cases for which its solution involves decomposing the problem into several one-level fractional location problems

A new algorithm for generalized fractional programs

A new dual problem for convex generalized fractional programs with no duality gap is presented and it is shown how this dual problem can be efficiently solved using a parametric approach. The resulting algorithm can be seen as “dual” to the Dinkelbach-type algorithm for generalized fractional programs since it approximates the optimal objective value of the dual (primal) problem from below. Convergence results for this algorithm are derived and an easy condition to achieve superlinear convergence is also established. Moreover, under some additional assumptions the algorithm also recovers at the same time an optimal solution of the primal problem. We also consider a variant of this new algorithm, based on scaling the “dual” parametric function. The numerical results, in case of quadratic-linear ratios and linear constraints, show that the performance of the new algorithm and its scaled version is superior to that of the Dinkelbach-type algorithms. From the computational results it also appears that contrary to the primal approach, the “dual” approach is less influenced by scaling

Optimizing a general optimal replacement model by fractional programming techniques

In this paper we adapt the well-known parametric approach from fractional programming to solve a class of fractional programs with a noncompact feasible region. Such fractional problems belong to an important class of single component preventive maintenance models. Moreover, for a special but important subclass we show that the subproblems occurring in this parametric approac

Criptorquidismo em jaguatirica de vida livre capturada no Parque Estadual do Rio Doce, Brasil

O presente trabalho consiste no primeiro relato de criptorquidismo em uma jaguatirica, adulta, de vida livre. Para a captura foram empregadas armadilhas com desarme de guilhotina, usando como isca vísceras de bovino. O animal foi contido quimicamente por meio de dardos anestésicos e mantido sob anestesia, utilizando a associação de cloridrato de quetamina e cloridrato de xilazina. Durante o exame andrológico, observou-se que o testículo esquerdo localizava-se subcutâneo, próximo à região inguinal, caracterizando-se criptorquidismo unilateral. Esse testículo apresentava-se flácido, com volume de 2,57mL, enquanto o testículo contralateral apresentava consistência firme e volume de 11,50mL. A área ocupada pelas espículas penianas mostrou-se compatível com a de animais reprodutores. O criptorquidismo é uma condição hereditária ligada à baixa variabilidade genética, já relatada em felinos silvestres consanguíneos. Nesse sentido, devido ao crescente isolamento populacional em fragmentos florestais, este achado torna-se preocupante, uma vez que pode ser indicativo de endogamia em populações de jaguatiricas de vida livre

Criptorquidismo em jaguatirica de vida livre capturada no Parque Estadual do Rio Doce, Brasil Cryptorchidism in free-living ocelot captured in the Parque Estadual do Rio Doce, Brazil

O presente trabalho consiste no primeiro relato de criptorquidismo em uma jaguatirica, adulta, de vida livre. Para a captura foram empregadas armadilhas com desarme de guilhotina, usando como isca vísceras de bovino. O animal foi contido quimicamente por meio de dardos anestésicos e mantido sob anestesia, utilizando a associação de cloridrato de quetamina e cloridrato de xilazina. Durante o exame andrológico, observou-se que o testículo esquerdo localizava-se subcutâneo, próximo à região inguinal, caracterizando-se criptorquidismo unilateral. Esse testículo apresentava-se flácido, com volume de 2,57mL, enquanto o testículo contralateral apresentava consistência firme e volume de 11,50mL. A área ocupada pelas espículas penianas mostrou-se compatível com a de animais reprodutores. O criptorquidismo é uma condição hereditária ligada à baixa variabilidade genética, já relatada em felinos silvestres consanguíneos. Nesse sentido, devido ao crescente isolamento populacional em fragmentos florestais, este achado torna-se preocupante, uma vez que pode ser indicativo de endogamia em populações de jaguatiricas de vida livre.<br>This paper is the first report of unilateral cryptorchidism in an adult wildlife ocelot, captured in Parque Estadual do Rio Doce. Cage traps were used to capture the animal, using bovine offal as bait. The animal was anesthetized with anesthetic darts and kept under anesthesia through a combination of ketamine and xylazine. The andrologycal examination showed that the left testicle was located subcutaneously near the inguinal region. In this case of unilateral cryptorchidism, the testis was soft and had a volume of 2.57mL, while the contralateral testis had a firm consistency and volume of 11.50mL. The length of the region occupied by the penile spikes was similar to other breeding animals. Cryptorchidism is an inherited condition linked to low genetic variability previously reported in consanguineous wild cats. Due to the increasing isolation of wild population in forest fragments, this finding is concerning because it can be indicative of inbreeding in wild ocelot populations

Criptorquidismo em jaguatirica de vida livre capturada no Parque Estadual do Rio Doce, Brasil

O presente trabalho consiste no primeiro relato de criptorquidismo em uma jaguatirica, adulta, de vida livre. Para a captura foram empregadas armadilhas com desarme de guilhotina, usando como isca vísceras de bovino. O animal foi contido quimicamente por meio de dardos anestésicos e mantido sob anestesia, utilizando a associação de cloridrato de quetamina e cloridrato de xilazina. Durante o exame andrológico, observou-se que o testículo esquerdo localizava-se subcutâneo, próximo à região inguinal, caracterizando-se criptorquidismo unilateral. Esse testículo apresentava-se flácido, com volume de 2,57mL, enquanto o testículo contralateral apresentava consistência firme e volume de 11,50mL. A área ocupada pelas espículas penianas mostrou-se compatível com a de animais reprodutores. O criptorquidismo é uma condição hereditária ligada à baixa variabilidade genética, já relatada em felinos silvestres consanguíneos. Nesse sentido, devido ao crescente isolamento populacional em fragmentos florestais, este achado torna-se preocupante, uma vez que pode ser indicativo de endogamia em populações de jaguatiricas de vida livre.This paper is the first report of unilateral cryptorchidism in an adult wildlife ocelot, captured in Parque Estadual do Rio Doce. Cage traps were used to capture the animal, using bovine offal as bait. The animal was anesthetized with anesthetic darts and kept under anesthesia through a combination of ketamine and xylazine. The andrologycal examination showed that the left testicle was located subcutaneously near the inguinal region. In this case of unilateral cryptorchidism, the testis was soft and had a volume of 2.57mL, while the contralateral testis had a firm consistency and volume of 11.50mL. The length of the region occupied by the penile spikes was similar to other breeding animals. Cryptorchidism is an inherited condition linked to low genetic variability previously reported in consanguineous wild cats. Due to the increasing isolation of wild population in forest fragments, this finding is concerning because it can be indicative of inbreeding in wild ocelot populations